Plus:
Lighter, same engine as a 335i, M sports suspension and it has new 6 piston brakes on front wheels. It has nicer interior, in my opinion, and estimated to be 20k cheaper then the M. (I am planning to buy a house soon. )

Minus:
Ugly and no LSD. Oh yea did I mention UGLY?

I will make an decision when the official US pricing is out. I would love to own a M3 but I think it's wiser for a 20 years old to buy a place first than a fine car. 135i or 335i will do for now.

Go with the 335i, or you will run the risk of being photographed in front of the 135i by a family member, and later on explain to your grandkids why you owned such a dorky looking car in your youth! (Your grandkids will not know anything about M suspension so they won't understand.)